Pump device



Jan. 30, 1940. G. R. ERICSON PUMP DEVICE Filed Afiril 17, 1937 f/a. J

" INVENTOR. 650264 5 55/650 4 ATTORNEY.

Patented Jan. 30, 1940 UNITED STATE PUMP DEVICE George R. Ericson, Kirkwood, Mo., assignor' to Carter Carburetor Corporation, St. Louis, Mo., acorporation of Delaware Application April 17,

2 Claims.

This invention relates to fluid pumps and consists, particularly, in novel accelerating pump structure for carburetors.

An object of the invention is to provide novel means for attaining delayed. action discharge from the pump or, in other words, means for continuing the pump discharge after the actuating member has come to rest.

Another object is to provide novel means for providing delayed action discharge from the pump while, at the same time, insuring a substantial initial discharge therefrom. These objects and other more detailed objects hereafter appearing are attained by the structure illustrated in the accompanying drawing, in which:

Fig. l is a sectional view of an internal combustion engine carburetor embodying a form of the invention and Fig. 2 is a view of a slightly modified part in a different position.

The carburetor shown comprises a downdraft mixture conduit including air inlet horn I, venturis 2, and outlet part 3 flanged as at 4 for attachment to the intake manifold, not shown, of an associated engine. A choke valve 5 is pivotally mounted in the air horn and throttle valve 6 is pivoted near the outlet portion on shaft I. Any suitable means (not shown) may be provided for operating the choke and throttle valves. Adjacent the mixture conduit is a bowl 8 within which fuel is maintained at a substantially constant level by the usual needle valve and float mechanism (not shown).

Also located within the float bowl is an accelerating pump cylinder 9, slidably receiving a cup-shaped piston it] which is constantly urged upwardly by coiled spring I l compressed between the bottoms of the piston and cylinder. Fuel enters the pump cylinder from the bowl through a screened inlet passage l2 controlled by check I3 and is discharged past outlet check l4 through a nozzle l5 into the mixture conduit adjacent the venturis. The inlet and outlet checks communicate with cylinder l0 through'a passage l6.

Pump piston It} is connected to the throttle valve through the intermediary of piston rod VI! and lever l8, pivoted to pillow block l9 projecting above the float bowl cover and connected to crank 20 rigid with the throttle shaft by means of a link 2|. is telescopically received within the hollow interior of piston I0 and is connected to the piston by means of spring 22 which, at its lower end, is secured directly to the free endof rod l1 and at its upper end is secured in a groove near the The lower portion of piston rod I! 1937, Serial No. 137,427

(01. Mil-34) upper extremity of the piston. Spring 22 is closely wound in a manner to have inherent initial tension so that even slight opening" movement of the throttle valve will apply substantial force to the pump piston tending to move the same in the discharge direction against spring ll. Spring ll preferably, is substantially weakerthan spring 22 so that the pump piston will respond immediately to opening of the throttle. Due'to' its inherent initial tension, spring 22 may be made of substantially lighter material than would be the case if the spring were otherwise formed. Such a spring exerts a more nearly constant force as it returns to its initial shape than a heavier spring at no initial compression and produces more uniform delayed pumping action.

In case the throttle is opened slowly, piston I!) will move downwardly in the cylinder at a. corresponding rate" and insufiicient pressure will result in the pumping chamber to cause extension of spring 22. However, if the throttle is opened quickly, the substantially increased pressure produced within pumping chamber, due to restrictions in the outlet passages, will cause distortion of spring 22 to permit telescoping movement between piston rod ll and the piston. At the end of the movement of actuating rod I1, spring 22 will contract to its original shape producing continued discharge movement of piston l0.

Fig. 2 shows a conical spring 220., connecting piston rod l! with the pump piston [0, in place of the cylindrical spring in the previous figure. The spring in this form is also of the closely wound, initially stressed variety, but is shown in the extended shape it assumes in case of rapid opening of the throttle valve.

The yielding pump structure described is stable due to the closely wound character of the spring connecting the piston with its actuating member and also insures substantial initial and desirably uniform delayed action of the pump. Due to the construction of the spring, substantial pressure must be produced in the pumping chamber before spring 220. is extended.

The pistons in both forms are of the metal type with circumferential grooves, but any suitable type of piston may be used. Also it may be convenient to form the piston as a collar having a center aperture receiving the. piston rod, rather than cup-shaped as shown, but in such case the plunger collar must be sufiiciently thick to insure stability within the cylinder.

The invention may be modified in these and other respects as will occur to those skilled in the art and the exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, means forming a mixing conduit, a throttle valve for controlling the flow of mixture therethrough, an accelerator pump for supplying accelerating fuel tosaid mixing conduit, said pump including a cylinder, a hollow piston having a closed end with an internal groove near the other end, an initially tensioned coiled spring having an enlarged coil at one end, said enlarged coil fitting into said groove to hold said piston and spring in assembled relation, an operating connection between said accelerator pump and said throttle whereby said pump is operated to discharge fuel upon opening movement of said throttle, said operating connection including a piston rod connected to the other end of said spring, and said spring having sufficient initial tension to directly transmit slow movements of said throttle to cause a proportional simultaneous movement of the piston, but yielding in response to pressures built up by rapid movements of said throttle so as to provide a delayed action of said accelerator charge and continued movement of said piston after termination of the throttle movement to the extent determined by the yielding of said spring, by virtue of energy stored in said spring by said yielding movement.

2. In a carburetor, means forming a mixing conduit, a throttle valve for controlling the flow of mixture therethrough, an accelerator pump including a cylinder and piston for supplying accelerating charges to said mixing conduit upon opening movement of said throttle, a connection between the throttle valve and said piston including a piston rod, a connection between said piston and piston rod comprising an initially tensionedclosely Wound coiled spring, one end of which is secured to said piston and the other end to said piston rod, whereby initial movement of said throttle at a moderate rate will produce a substantially simultaneous corresponding movement of said piston in the discharge direction, and an excessively rapid movement of said throttle will partially extend said spring to permit lagging and gradual movement of said piston, and a continued discharge from said accelerator pump after completed movement of said piston rod, by virtue of continued movement of the piston to full discharged position due to energy stored by the extension of said initial tensioned spring.

GEORGE R. ERICSON. 

